Tray stacking system

ABSTRACT

A tray stacking system comprises a plurality of tray stacking members each supported on drive chains for pivotal movement between a tray receiving and supporting position and a dormant position. The tray stacking members are arranged in opposed pairs and comprise axially extending ledges having sufficient length to receive three trays. The drive chains support the tray stacking members for downward movement in a tray stacking course extending from a tray receiving zone to a tray stacking zone. In use, the tray stacking members comprising each pair are initially pivoted to the tray receiving and supporting positions and are thereafter positioned in the tray receiving zone. Trays are then received on the ledges of the tray stacking members from a tray washing system. As the tray stacking members are filled to capacity with trays a trigger is engaged, whereupon the drive chains are actuated to move the loaded tray stacking members downwardly and to position the next pair of tray stacking members in the tray receiving zone. Step-by-step downward movement of the loaded tray stacking members in the tray stacking course is continued until the tray stacking members engage stacks of trays in the tray stacking zone. At this point the tray stacking members are pivoted outwardly to the dormant positions, thereby depositing the trays onto the stacks.

United States Patent Rice et al.

1 1 TRAY STACKING SYSTEM [76] Inventors: Howard Gene Rice, 1109 Hadrian Court, 1rving,Tex, 75060; Lawrence Peter Kitterman, 1 1426 Willow Lane, Cypress. Tex, 77429 [22] Filed: May 25, 1973 [21] Appl. No.: 363,962

[44] Published under the Trial Voluntary Protest Program on January 28, 1975 as document no. 8 363,962,

[52] US. Cl. 214/6 FA; 134/63; 198/163 [51] Int. Cl. 8650 57/14 [58] Field of Search 214/6 FA;198/158, 163, 198/165; 134/63 [56] References Cited UNITED STATES PATENTS 835.312 11/1906 McNabb 214/6 FA X 1,342,463 6/1920 Sanwo 214/6 FA X 2.854.152 9/1958 Miller 214/6 FA 3,486,939 12/1969 Pinckartl... 134/63 X 3,533,517 10/1971) Heide 198/163 X 3,591,018 7/1971 Nalbach 198/163 X 3,718,267 2/1973 Hiebert et a] 214/6 FA Primary Examiner-Albert J. Makay Assistant Examinerl es1ie J. Paperner Attorney, Agent, or Firm-Richards, Harris &

Medlock [57] ABSTRACT A tray stacking system comprises a plurality of tray stacking members each supported on drive chains for pivotal movement between a tray receiving and supporting position and a dormant position. The tray stacking members are arranged in opposed pairs and comprise axially extending ledges having sufficient length to receive three trays. The drive chains support the tray stacking members for downward movement in a tray stacking course extending from a tray receiving zone to a tray stacking zone,

in use, the tray stacking members comprising each pair are initially pivoted to the tray receiving and supporting positions and are thereafter positioned in the tray receiving zone. Trays are then received on the ledges of the tray stacking members from a tray washing system. As the tray stacking members are filled to capacity with trays a trigger is engaged, whereupon the drive chains are actuated to move the loaded tray stacking members downwardly and to position the next pair of tray stacking members in the tray receiving zone. Step-by-step downward movement of the loaded tray stacking members in the tray stacking course is continued until the tray stacking members engage stacks of trays in the tray stacking zone. At this point the tray stacking members are pivoted outwardly to the dormant positions, thereby depositing the trays onto the stacks.

10 Claims, 7 Drawing Figures US. Patent Nov. 25, 1975 Sheet 1 of3 3,921,826

US. Patent Nov. 25, 1975 Sheet 2 01 3 3,921,826

TRAY STACKING SYSTEM BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to tray stacking systems, and more particularly to a system for stacking compartmented food service trays and similar articles.

The co-pending application of L. P. Kitterman and H. G. Rice, Ser. No. 89,40I filed Nov. I3. 1970, now Pat. No. 3,798,065. for TRAY WASHING SYSTEM relates to a fully automated system for washing compartmented food service trays of the type used in schools to serve school lunches, and for similar purposes. The system comprises apparatus for receiving trays in a predetermined orientation and for transporting the trays in timed sequence, apparatus for pouring water over the trays to dislodge refuse and silverware therefrom, apparatus for washing, rinsing, and drying the trays, and apparatus for stacking the clean trays in a predetermined orientation.

The tray stacking apparatus disclosed in the prior Kitterman and Rice application is specifically designed to stack trays on a conventional mobile self-depressing tray receiver. The use of the latter apparatus in conjunction with a tray washing system incorporating the prior Kitterman and Rice invention is desirable in many instances. It has been found. however, that it is often preferable to stack clean food service trays on a tray cart rather than on a mobile self-depressing tray receiver. Perhaps most importantly. tray carts are relatively inexpensive to purchase and use as compared with self-depressing tray receivers.

The present invention comprises a tray stacking system useful in conjunction with tray washing systems of the type disclosed in the above-identified application of Kitterman and Rice to stack compartmented food service trays on a tray cart or other device. In accordance with the broader aspects of the invention, a tray stacking system includes a plurality of tray stacking members each comprising an elongate tray receiving ledge. The tray stacking members are arranged in opposed pairs. and each pair of tray stacking members is initially positioned in the tray receiving zone to receive at least one compartmented food service tray from a tray washing system. The tray stacking members and the tray supported thereby are subsequently moved downwardly out of the tray receiving zone and into a tray stacking zone. Upon contact between the tray stacking members and a stack of trays in the tray stacking zone, the tray stacking members are pivoted outwardly to deposit the tray onto the stack.

More specifically. the tray stacking members are supported on drive chains mounted for movement around spaced. parallel courses. By this means there is defined a tray stacking course extending downwardly from the tray receiving zone to the tray stacking zone. The tray stacking members are supported on the drive chains for pivotal movement between a tray receiving and supporting position wherein the tray receiving ledges face inwardly and the tray stacking members extend into the tray stacking course. and a dormant position wherein the tray receiving ledges face upwardly and the tray stacking members are positioned entirely out of the tray stacking course.

The tray stacking members are preferably eccentrically supported on the drive chains. By this means the tray stacking members are pivoted over center in response to contact with trays in the tray stacking zone. and therefore are positioned clear of the trays in the stack following pivotal movement to the dormant position. Structure is provided for returning each tray stacking member to the tray receiving and supporting position prior to the positioning of the tray stacking member in the tray receiving zone. Thus. upon the return of each pair of tray stacking members to the tray receiving zone. the foregoing cycle of operation is repeated.

In accordance with other aspects of the invention. the tray receiving ledges of each pair of tray stacking members are adapted to support at least two compartmented food service trays. When the tray receiving ledges of each pair of tray stacking members have been filled to capacity with trays received from the tray washing system, a trigger is engaged, whereupon the drive chains are actuated to move the pair of tray stacking members downwardly sufficiently to position the next pair of tray stacking members in the tray receiving zone. Step-by-step downward movement is continued until the tray stacking members engage stacks of trays in the tray stacking zone, at which time the tray stacking members are pivoted outwardly to release the trays onto the stacks. Stacking of trays continues until the stacks reach a predetermined height. whereupon a switch is actuated to discontinue both the operation of the tray stacking system and operation of the associated tray washing system.

In accordance with still other aspects of the invention. the drive chains are driven by apparatus including a drive motor and an electrically actuated clutch. The clutch is adapted to operatively connect the motor to the drive chains through a cross shaft and a pair of bevel gearsets. The bevel gearsets also actuate a pair of cams having aligned detents formed in them. The cams and therefore the drive chains are normally locked by a pair of cam rollers mounted at the end of a solenoidactuated bar for engagement with the detents of the cams.

When the trigger is actuated. the clutch is tripped and the solenoid is energized to disengage the cam rollers from the detents ofthe cams. The motor then operates the drive chains through the cross shaft and the bevel gearsets. The cam rollers are lowered onto the surfaces of the cams and drop into the next detents. thereby positively stopping and locating the drive chains. At substantially the same time. the clutch is disengaged.

DESCRIPTION OF THE DRAWINGS A more complete understanding ofthe invention may be had by referring to the following detailed description when taken in conjunction with the accompanying drawings. wherein:

FIG. 1 is a perspective view of a tray stacking system incorporating the invention;

FIG. 2 is an end view of the tray stacking system in which certain parts have been broken away more clearly to illustrate certain features of the invention;

FIG. 3 is a top view of the tray stacking system in which certain parts have been broken away;

FIG. 4 is an enlarged. exploded. perspective view illustrating certain structural details of the tray stacking system;

FIG. 5 is an illustration of the operation of the tray stacking system shown in FIG. 1;

3 FIG. 6 is a perspective view illustrating the drive mechanism of the tray stacking system; and

FIG. 7 is an end view ofa portion of the drive mechanism.

DETAILED DESCRIPTION Referring now to the drawings. and particularly to FIG. 1 thereof. there is shown a tray stacking system incorporating the present invention. The tray stacking system I0 is particularly adapted for use in conjunction with a tray washing system of the type disclosed and claimed in the co-pending application of Kitterman and Rice. Ser. No. 89.401. filed Nov. 13. 1970 now U.S. Pat. No. 3.798.065. However. those skilled in the art will appreciate the fact that the tray stacking system 10 is adapted for use in conjunction with other types of tray washing systems. and furthermore that the system may be employed to stack items other than trays. if desired. For example, the invention may be used in conjunction with sheet steel. wood. etc.. as well as with crates. boxes and similar products or goods which are adapted for stacking.

The tray stacking system I0 includes a frame 12 which supports the remaining components of the system. In the particular embodiment of the invention illustrated in certain of the Drawings. the frame 12 is of generally open construction. It will be understood. however. that a frame which is substantially more enclosed than that illustrated in the drawings may be utilized in the practice of the invention. if desired.

Referring now to FIG. 2, the tray stacking system I0 further comprises four roller-type drive chains 22. The chains 22 are mounted for movement around spaced. parallel courses each defined by an upper sprocket 24 and a lower sprocket 26. As is best shown in FIG. 3, the sprockets defining the drive chain courses on each side of the tray stacking system 10 are interconnected by shafts 28. The shafts 28 are in turn drivingly interconnected in such a way that the four drive chains 22 comprising the tray stacking system 10 are constrained to move in synchronism and at exactly the same speed.

As is best shown in FIG. 4, the drive chains 22 of the tray stacking system I0 support a plurality of tray stacking members 30. The stacking members 30 may be cylindrical or angular in shape and each comprise an elongate tray receiving ledge 32. The ledges 32 extend substantially the entire length of their respective tray stacking members 30 and are adapted to receive the edges of trays or similar articles. Each tray stacking member 30 comprises a pair of opposed cutaway portions 34 defined by a pair of locating surfaces 36 and 38 extending substantially perpendicularly with respect to each other. Each end of each tray stacking member 30 is also provided with an eccentrically positioned. axially extending bore 40.

The drive chains 22 are each equipped with a plurality of sets of inwardly directed pins 42 each including a first pin 44 and a second pin 46. The first pin 44 of each set is received in the bore 40 at one end of one of the tray stacking members 30, whereby the tray stacking member is pivotally supported on the adjacent drive chain 22. The pin 46 of each set 42 acts as a locating pin which cooperates with the surfaces 36 and 38 of the cutaway portion 34 of the corresponding tray stacking member 30. By this means the pin 46 controls the pivotal positioning of its corresponding tray stacking member 30 relative to the drive chain 22.

Referring now to FIG. 5, the four drive chains 22 of the tray stacking system 10 define a tray stacking course 48 extending downwardly from a tray receiving zone 50 to a tray stacking zone 52. The tray stacking members 30 are arranged on the drive chains 22 in opposed pairs. The drive chains 22 therefore function to move each tray stacking member 30 on one side of the tray stacking system [0 downwardly through the tray stacking course 48 in synchronism with the corresponding tray stacking member on the opposite side of the tray stacking system I0.

The use of the tray stacking system I0 is illustrated in FIGS. I. 3 and 5. The drive chains 22 are initially actuated to position a particular pair of tray stacking members 30 in the tray receiving zone 50. The tray stacking members 30 are thus oriented to receive and support trays in that the tray receiving ledges 32 of the tray stacking members 30 face inwardly and the tray stacking members 30 extend into the tray stacking course 48. This positioning of the tray stacking members is characterized by engagement between the surfaces 36 of the tray stacking members and the pins 46 of the drive chains 22.

When a particular pair of tray stacking members 30 is positioned in the tray receiving zone 50, compartmented food service trays T are received by the tray stacking members from the tray washing system W. As is most clearly shown in FIG. 3, this is accomplished by moving the trays T axially relative to the tray stacking members 30 with the edges of the trays T received on the ledges 32 of the tray stacking members 30. The tray stacking members 30 are preferably adapted to receive three trays T positioned adjacent one another on the ledges 32. By this means multiple stacks of trays are simultaneously formed on a tray cart C or similar apparams. and the necessity of repositioning the tray cart C during the operation of the tray stacking system I0 is eliminated.

Regardless of the length of the tray stacking members 30, whenever a particular tray T has been advanced as far as possible on the tray receiving ledges 32 of a particular pair of tray stacking members 30, a trigger 54 is engaged. Upon actuation, the trigger 54 initiates operation of the drive chains 22 to move the loaded pair of tray stacking members 30 downwardly in the tray stacking course 48. This action is continued until the drive chains 22 have been moved sufficiently to position the next pair of tray stacking members 30 in the tray receiving zone 50. At this point. operation of the drive chains 22 is discontinued pending subsequent actuation of the trigger 54, whereupon another cycle of operation is initiated.

As will be apparent. continued operation of the system 10 results in step-by-step downward movement of each pair of tray stacking members 30 and the trays T supported thereby in the tray stacking course 48. This action continues until a particular pair of tray stacking members 30 engage a stack of trays S in the tray stacking zone 52.

Upon engagement between the tray stacking members 30 and the stack of trays S. the tray stacking members 30 are pivoted outwardly relative to the tray stacking course 48. Outward pivotal movement of the tray stacking members 30 pivots the tray stacking members over center and into dormant positions wherein the tray receiving ledges 32 of the tray stacking members 30 face upwardly and the tray stacking members are positioned entirely out of the stacking course 48. The dormant positions of the tray stacking members 30 are characterized by engagement of the pins 46 with the surfaces 38 of the cutaway portions 34 of the tray stacking members 30.

As the tray stacking members 30 are moved out of the tray receiving and supporting positions and into the dormant positions. the compartmented food service trays T carried by the tray stacking members 30 are deposited on top of the stacks of trays S. This has been found to be highly advantageous in a number of respects. First. regardless of the height of the stack of trays S on the tray cart C. the trays are released onto the top of the stacks from minimum height. By this means. noise is held to a minimum and damage to the trays is completely prevented. Second. since the tray stacking members 30 are positioned entirely out of the stacking course 48 when they are in the dormant positions. continued downward movement of the tray stacking members does not result in contact between the tray stacking members 30 and the trays in the stacks S. This prevents both wear of the trays and wear of the tray stacking members.

Subsequent to pivotal movement of a particular pair of tray stacking members 30 to the dormant positions, the tray stacking members 30 are returned to the tray receiving zone 50 by the drive chains 22. It will be appreciated that this return movement occurs in step-bystep fashion following each actuation of the trigger 54. As is most clearly shown in FIGS. 3 and 5, each upper sprocket 24 is equipped with a hub 56 positioned for frictional engagement with the tray stacking members 30 during return movement thereof to the tray receiving zone 50. Frictional engagement between the tray stacking members 30 and the hubs 56 of the upper sprockets 24 pivots the tray stacking members out of the dormant positions and into the tray receiving and supporting positions. By this means the tray stacking members 30 are properly positioned in the tray receiving and supporting positions simultaneously with their return to the tray receiving zone 50 under the action of the drive chains 22.

It will thus be appreciated that as long as compartmented food service trays are received in the tray receiving ledges 32 of the tray stacking members 30, the tray stacking system operates automatically to stack trays onto a tray cart C positioned in the lower portion of the frame 12. After all of the trays from a particular meal have been washed by the tray washing system W. the trigger 54 will no longer be actuated by movement of trays into the tray stacking system 10. This means that a substantial number of trays may remain in the tray stacking system 10 at the end of the tray washing operation.

The foregoing situation presents no problem in that the trigger 54 is simply actuated by an operator, whereby the drive chains 22 are operated continuously to stack the remaining trays onto the stacks S. The operator then moves the tray cart C out of the tray stacking system 10, whereupon the trays T stacked on the cart are either placed in storage or are returned to the serving facility for immediate reuse. An empty tray cart is then positioned in the lower portion of the frame 12, whereupon the tray stacking system 10 is again ready to stack trays.

It will be understood that in many instances the number of trays that are utilized in serving a particular meal will exceed the capacity of the tray cart C. To this end. the tray stacking system 10 is provided with a limit switch 58 which functions to discontinue both the operation of the tray stacking system 10 and the operation of the associated tray washing system W whenever the tray cart C is full. As is best shown in FIG. 2. the limit switch 58 is positioned for actuation in response to pivotal movement of one of the tray stacking members 30 whenever the stacks of trays S reach a predetermined height. At this time the loaded tray cart C is removed and is replaced with an empty tray cart prior to restarting of the tray washing system W and the tray stacking system 10.

Additional structural details of the tray stacking system 10 are illustrated in FIGS. 6 and 7. The trigger 54 is mounted on a shaft 60 and functions to control the operation of the tray stacking system 10 by means of a limit switch 62. Trays are received in the tray stacking system 10 from the tray washing system W through a slot 64 formed in an end wall 66 of the frame 12.

The drive system of the tray stacking system 10 includes an electric motor 68 which is coupled to a drive chain 70 through a gear box 72. The chain 70 connects the output of the motor 68 to an electric clutch 74. Upon actuation the electric clutch 74 functions to operatively connect the motor 68 to the drive chains 22 through a cross shaft 76 and a pair of bevel gearsets 78.

The drive mechanism further includes a pair of cams 80 each having a plurality of aligned detents 82 formed therein. A pair of cam rollers 84 are mounted at the opposite ends of a bar 86 for engagement with the detents 82 ofthe earns 80. The positioning of the cam rollers 84 is controlled by means of a solenoid 88 connected between the frame 12 and the bar 86.

Upon actuation of the trigger 54. the electric clutch 74 is tripped and the solenoid 88 is energized to disengage the cam rollers 84 front the detents 82 of the cams 80. The motor 68 then operates through the gear box 72, the chain 70, the electric clutch 74, the shaft 76 and the bevel gear sets 78 to operate the drive chains 22. The solenoid 88 is then de-energizcd so that the cam rollers 84 ride on the periphery of the cams 80. The cam rollers 84 drop into the next detents 82 of the cams 80, thereby immediately stopping and locating the drive chains 22 of the tray stacking system [0. At substantially the same time the electric clutch 74 is disengaged.

From the foregoing, it will be understood that the use of the present invention results in numerous advantages over the prior art. Thus. by means of the invention. compartmented food service trays and similar articles are automatically stacked on conventional tray carts or the like. This action is carried out without noise or danger of damage to the trays. The use ofthe tray stacking systems incorporating the invention is therefore highly advantageous in those operations wherein it is not deemed desirable to stack trays onto a mobile selfdepressing tray receiver.

It will be further appreciated that the present invention is adapted to many uses beyond the stacking of compartmented food service trays. For example, various other types of trays may be stacked by means of tray stacking systems incorporating the invention. Furthermore. a wide variety of stackable articles other than trays may be stacked by means of the invention. The only requirement is that the articles comprise edges or other projecting portions which may be received by the tray stacking members of a tray stacking system constructed in accordance with the invention.

Although specific embodiments of the invention have been illustrated in the accompanying drawings and de- 7 scribed in the foregoing detailed description. it will be understood that the invention is not limited to the embodiments disclosed. but is capable of numerous rearrangements. modifications. and substitutions of parts and elements without departing from the spirit of the invention What is claimed is:

l. A tray stacking system comprising:

a plurality of tray stacking members each comprising an elongate tray receiving ledge adapted to receive one edge of a tray;

endless conveyor means defining a tray stacking course extending downwardly from a tray receiving zone to a tray stacking zone;

means supporting the tray stacking members on the endless conveyor means in opposed pairs and for pivotal movement between dormant positions and tray receiving and supporting positions wherein the tray receiving ledges of the tray stacking members face one another:

said means for supporting the stacking members on the endless conveyor means comprising a plurality of pairs of pins each including a first pin for pivotally supporting one end of one of the stacking members and a second pin for controlling the pivotal positioning of the tray stacking member when the tray stacking member is in the tray receiving and supporting position:

means for pivoting each tray stacking member to the tray receiving and supporting position prior to the movement of the tray stacking member into the tray receiving zone under the action of the endless conveyor means. and

means responsive to engagement of each tray stacking member with a tray in the tray stacking zone for pivoting the stacking member to the dormant position.

2. The tray stacking system according to claim 1 wherein the tray receiving ledges of each pair of tray stacking members are adapted to receive at least two trays and further including means responsive to the positioning of two trays in the tray receiving ledges of a pair of tray stacking members for actuating the endless conveyor means to move the pair of tray stacking members downwardly out of the tray receiving zone and to position another pair of tray stacking members in the tray receiving zone.

3. The tray stacking system according to claim 1 wherein each tray stacking member is eccentrically supported for pivotal movement over center to the dormant position in response to contact between the tray stacking member and a tray in the stacking zone.

4. The tray stacking system according to claim 1 wherein the tray receiving zone is located adjacent to a tray washing system so that clean trays are received in the tray stacking system directly from the tray washing system and further including means for positioning a tray cart at the bottom of the tray stacking zone so that the tray stacking system functions to stack trays on the tray cart.

5. A stacking system comprising:

opposed drive chain pairs mounted for movement around spaced. parallel courses and defining a stacking course extending downwardly from an article receiving zone to a stacking zone;

a plurality of stacking members each supported at its opposite ends by the drive chains comprising one ofthe pairs and each comprising an elongate article 8 receiving ledge extending substantially the entire length of the stacking member.

cooperating means on each end of each stacking member and on the adjacent drive chain for pivotally supporting the stacking member on the drive chain and for regulating the pivotal positioning of the stacking member relative to the drive chain. said means comprising a first pin projecting from the drive chain and means on the stacking member for receiving the first pin and thereby pivotally supporting the stacking member and a second pin projecting from the drive chain and at least one locating surface formed on the stacking member for cooperation with the second pin to control the pivotal positioning of the stacking member;

said stacking members being mounted at spaced ititervals on the drive chains and in opposed pairs whereby each stacking member on one of the drive chain pairs is moved downwardly through the stacking course in synchronism with a corresponding stacking member on the other drive chain pair.

means for positioning each stacking member with its article receiving ledge facing inwardly relative to the stacking course when the stacking member is in the article receiving zone and thereby receiving an article on the ledge: and

means responsive to contact between each stacking member and an article in the stacking zone for pivoting the stacking member outwardly relative to the stacking zone and thereby releasing the article from the article receiving ledge of the stacking member 6. The stacking system according to claim 5 further characterized by means responsive to the positioning of an article on the article receiving ledge of a first pair of stacking members for actuating the drive chain to position a second pair of stacking members in the article receiving zone.

7. The stacking system according to claim 6 wherein the stacking members are of sufficient length to receive at least two articles positioned end to end on the article receiving ledges of the stacking members. and wherein the drive chain actuating means is responsive to the positioning of at least two articles in a pair of stacking members to actuate the drive chains to position another pair of stacking members in the receiving zone.

8. A tray stacking system comprising:

means defining a tray stacking course extending downwardly from a tray receiving zone to a tray stacking zone;

a plurality of stacking members each comprising an elongate tray receiving ledge and each eccentrically supported for pivotal movement between a tray receiving and supporting position wherein the tray receiving member extends into and the tray receiving ledge faces toward the tray stacking course and an over centered dormant position wherein the tray stacking member is located entirely out of the tray stacking course.

means for moving the tray stacking members around paths including portions extending between the tray receiving zone and the tray stacking zone adjacent to the tray stacking course;

said tray moving means comprising opposed drive chain pairs;

said stacking members being arranged on the drive chains in opposed pairs so that each stacking membet on one ofthe drive chain pairs is moved downwardly through the tray stacking course in synchronism with a tray stacking member on the other drive chain pair.

a plurality of pairs of pins projecting from each drive chain. each pair of pins comprising a first pin for pivotally supporting one end of one of the tray stacking members and a second pin for locating the tray stacking member in the tray receiving and supporting position:

means for pivoting each tray stacking member to the tray receiving supporting position prior to movement of the tray stacking member into the tray receiving zone and thereby receiving a tray in the tray receiving ledge of the tray receiving member; and

means responsive to the positioning of a tray in the ledge of a tray receiving member for actuating the stacking member moving means to position another tray stacking member in the tray receiving zone, whereby upon contact between each tray stacking member and a stack of trays in the stack- 10 ing zone the stacking member is pivoted over center to the dormant position thereby releasing the tray.

9. The tray stacking system according to claim 8 further comprising sprocket means defining the course of each drive chain and wherein at least certain of the sprocket means comprise hubs positioned for engagement with each tray stacking member to pivot the tray stacking member to the tray receiving and supporting position.

10. The tray stacking system according to claim 8 wherein the tray receiving ledge of each tray stacking member is of sufficient length to receive at least two trays and wherein the stacking member moving means actuating means is responsive to the filling of the tray receiving ledge ofa tray stacking member with trays for actuating the stacking member moving means to position another tray stacking member in the tray receiving zone. 

1. A tray stacking system comprising: a plurality of tray stacking members each comprising an elongate tray receiving ledge adapted to receive one edge of a tray; endless conveyor means defining a tray stacking course extending downwardly from a tray receiving zone to a tray stacking zone; means supporting the tray stacking members on the endless conveyor means in opposed pairs and for pivotal movement between dormant positions and tray receiving and supporting positions wherein the tray receiving ledges of the tray stacking members face one another; said means for supporting the stacking members on the endless conveyor means comprising a plurality of pairs of pins each including a first pin for pivotally supporting one end of one of the stacking members and a second pin for controlling the pivotal positioning of the tray stacking member when the tray Stacking member is in the tray receiving and supporting position; means for pivoting each tray stacking member to the tray receiving and supporting position prior to the movement of the tray stacking member into the tray receiving zone under the action of the endless conveyor means; and means responsive to engagement of each tray stacking member with a tray in the tray stacking zone for pivoting the stacking member to the dormant position.
 2. The tray stacking system according to claim 1 wherein the tray receiving ledges of each pair of tray stacking members are adapted to receive at least two trays and further including means responsive to the positioning of two trays in the tray receiving ledges of a pair of tray stacking members for actuating the endless conveyor means to move the pair of tray stacking members downwardly out of the tray receiving zone and to position another pair of tray stacking members in the tray receiving zone.
 3. The tray stacking system according to claim 1 wherein each tray stacking member is eccentrically supported for pivotal movement over center to the dormant position in response to contact between the tray stacking member and a tray in the stacking zone.
 4. The tray stacking system according to claim 1 wherein the tray receiving zone is located adjacent to a tray washing system so that clean trays are received in the tray stacking system directly from the tray washing system and further including means for positioning a tray cart at the bottom of the tray stacking zone so that the tray stacking system functions to stack trays on the tray cart.
 5. A stacking system comprising: opposed drive chain pairs mounted for movement around spaced, parallel courses and defining a stacking course extending downwardly from an article receiving zone to a stacking zone; a plurality of stacking members each supported at its opposite ends by the drive chains comprising one of the pairs and each comprising an elongate article receiving ledge extending substantially the entire length of the stacking member, cooperating means on each end of each stacking member and on the adjacent drive chain for pivotally supporting the stacking member on the drive chain and for regulating the pivotal positioning of the stacking member relative to the drive chain, said means comprising a first pin projecting from the drive chain and means on the stacking member for receiving the first pin and thereby pivotally supporting the stacking member and a second pin projecting from the drive chain and at least one locating surface formed on the stacking member for cooperation with the second pin to control the pivotal positioning of the stacking member; said stacking members being mounted at spaced intervals on the drive chains and in opposed pairs whereby each stacking member on one of the drive chain pairs is moved downwardly through the stacking course in synchronism with a corresponding stacking member on the other drive chain pair; means for positioning each stacking member with its article receiving ledge facing inwardly relative to the stacking course when the stacking member is in the article receiving zone and thereby receiving an article on the ledge; and means responsive to contact between each stacking member and an article in the stacking zone for pivoting the stacking member outwardly relative to the stacking zone and thereby releasing the article from the article receiving ledge of the stacking member.
 6. The stacking system according to claim 5 further characterized by means responsive to the positioning of an article on the article receiving ledge of a first pair of stacking members for actuating the drive chain to position a second pair of stacking members in the article receiving zone.
 7. The stacking system according to claim 6 wherein the stacking members are of sufficient length to receive at least two articles positioned end to end on the article receiving ledges of the stacking members, and wherein thE drive chain actuating means is responsive to the positioning of at least two articles in a pair of stacking members to actuate the drive chains to position another pair of stacking members in the receiving zone.
 8. A tray stacking system comprising: means defining a tray stacking course extending downwardly from a tray receiving zone to a tray stacking zone; a plurality of stacking members each comprising an elongate tray receiving ledge and each eccentrically supported for pivotal movement between a tray receiving and supporting position wherein the tray receiving member extends into and the tray receiving ledge faces toward the tray stacking course and an over centered dormant position wherein the tray stacking member is located entirely out of the tray stacking course; means for moving the tray stacking members around paths including portions extending between the tray receiving zone and the tray stacking zone adjacent to the tray stacking course; said tray moving means comprising opposed drive chain pairs; said stacking members being arranged on the drive chains in opposed pairs so that each stacking member on one of the drive chain pairs is moved downwardly through the tray stacking course in synchronism with a tray stacking member on the other drive chain pair; a plurality of pairs of pins projecting from each drive chain, each pair of pins comprising a first pin for pivotally supporting one end of one of the tray stacking members and a second pin for locating the tray stacking member in the tray receiving and supporting position; means for pivoting each tray stacking member to the tray receiving supporting position prior to movement of the tray stacking member into the tray receiving zone and thereby receiving a tray in the tray receiving ledge of the tray receiving member; and means responsive to the positioning of a tray in the ledge of a tray receiving member for actuating the stacking member moving means to position another tray stacking member in the tray receiving zone, whereby upon contact between each tray stacking member and a stack of trays in the stacking zone the stacking member is pivoted over center to the dormant position thereby releasing the tray.
 9. The tray stacking system according to claim 8 further comprising sprocket means defining the course of each drive chain and wherein at least certain of the sprocket means comprise hubs positioned for engagement with each tray stacking member to pivot the tray stacking member to the tray receiving and supporting position.
 10. The tray stacking system according to claim 8 wherein the tray receiving ledge of each tray stacking member is of sufficient length to receive at least two trays and wherein the stacking member moving means actuating means is responsive to the filling of the tray receiving ledge of a tray stacking member with trays for actuating the stacking member moving means to position another tray stacking member in the tray receiving zone. 